The control of phytopathogenic fungi is of great economic importance since fungal growth on plants or on parts of plants inhibits production of foliage, fruit or seed, and the overall quality of a cultivated crop. About 25 percent of all fungal diseases in agriculture and horticulture are caused by powdery mildew phytopathogens.
Because of the vast economic ramifications of fungal propagation in agricultural and horticultural cultivations, a broad spectrum of fungicidal and fungistatic products have been developed for general and specific applications.
Of particular interest with respect to the present invention embodiments are fungicide compositions which contain an inorganic bicarbonate or carbonate compound. It is known that bicarbonate and carbonate compounds exhibit fungicidal properties for agricultural purposes.
Phytopathology, 48, 169 (1931) by R. H. Marloth describes studies involving the physiology of fungi. The reference reports studies which demonstrate that sodium and potassium bicarbonate and carbonate salts are toxic to fungi such as Penicillum italicum and Penicillum digitalum.
U.S. Pat. No. 1,560,558 discloses the use of salts such as lithium carbonate, sodium carbonate, sodium bicarbonate, potassium bicarbonate, potassium carbonate and ammonium bicarbonate as fungicide ingredients.
U.S. Pat. No. 4,599,233 describes a fungicide composition which consists of sodium bicarbonate in combination with a surface active food emulsifier such as sorbitan monostearate.
Japanese patent 53118523 describes the combination of sodium bicarbonate and lecithin as an active agent for the control of agricultural and fruit storage fungus diseases.
Japanese patent 56043207 describes a biocidal composition containing sodium bicarbonate and a polyglycerol fatty acid ester. The biocide controls Penicillum digitatum on oranges, Sphaerotheca fuligenea on cucumbers, Piricularia oryzae on rice, and mosaic virus on tomatoes.
Japanese patent 60097909 describes a soil fungicide prepared by admixing slaked lime with sodium bicarbonate, potassium bicarbonate, boric acid and phenolphthalein.
German patent DE 2927994 describes a fungicide which consists of sodium bicarbonate incorporated into a food-compatible surfactant such as saccharose laurate.
Japanese patent 57062208 describes horticultural fungicides in which the addition of sodium bicarbonate to polyoxin or thiophanatemethyl increases the fungicidal activity of the organic biocide against Botrytis cinerea on cucumbers.
Japanese patent 58023609 describes an agricultural fungicide composed of a mixture of sodium bicarbonate or potassium bicarbonate with cupric hydroxide, basic copper carbonate or basic copper sulfate. The combination of ingredients exhibits a synergistic fungicidal effect against cucumber early blight, tomato wilt, rice sheath blight, rice blast and citrus canker.
There remains a continuing need for improved methods for providing preventive and curative fungicidal activity for the protection of cultivated plants with a minimum of phytotoxic side effects, and with safety for animals and humans.
Accordingly, it is an object of this invention to provide a method of controlling mildew diseases in cultivated plants.
It is another object of this invention to provide a method for controlling mildew in agricultural and horticultural plants with an aqueous fungicidal formulation having a content of ingredients which are harmless to animals and humans.
It is another object of this invention to provide a method of controlling powdery mildew and downy mildew in pre-harvest and post-harvest crops with an aqueous formulation which forms a solid coating on plant matter exhibiting fungicidal activity of sustained duration.
Other objects and advantages of the present invention shall become apparent from the accompanying description and examples.